When the user uses two thermocouples or multi-point thermocouples on site, the conventional thermocouple compensation wires can not be used. In this case, multicore thermocouple cable is needed. When the multi-core thermocouple compensation wire is selected, in addition to the combination of multiple pairs of positive and negative poles, the selection and the single thermocouple compensation wire selection are the same, and the following main points are required.
multicore thermocouple cable compensation wire precautions
1. Compensation wire selection
The compensation wire must be correctly selected according to the type of thermocouple used and the occasion used. For example, the k-type couple should select the compensation conductor of the k-type even, and select the operating temperature range according to the application. Usually, the kx operating temperature is -20 to 100 ° C, and the wide range is -25 to 200 ° C. The normal level error is ±2.5 °C and the precision level is ±1.5 °C.
2. Length of use
Because the signal of the thermocouple is very low, it is microvolt level. If the distance used is too long, the attenuation of the signal and the interference of strong electric current in the environment can make the signal of the thermocouple distorted, resulting in inaccurate measurement and control temperature. Temperature fluctuations occur when the control is severe. According to our experience, it is usually better to use the thermocouple compensation wire length control within 15 meters. If it exceeds 15 meters, it is recommended to use a temperature transmitter to transmit signals. The temperature transmitter converts the potential value corresponding to the temperature into a DC current transmission, which is strong against interference.
The compensation wire routing must be kept away from the power line and the interference source. In places where it is not possible to avoid crossing, use crossover as much as possible, not parallel.
5. Shielding compensation wire
In order to improve the anti-interference of the thermocouple cable, a shield compensation wire can be used. For occasions with a lot of on-site interference sources, the effect is better. However, the shielding layer must be strictly grounded, otherwise the shielding layer will not only play the role of shielding, but will enhance the interference.
multicore thermocouple cable structure
The function of the thermocouple compensation wire is to extend the cold electrode of the hot electrode, that is, the moving thermocouple, and form a temperature measurement system by connecting with the display instrument. The products are mainly used in various temperature measuring devices, and have been widely used in nuclear power, petroleum, chemical, metallurgy, electric power and other departments. For more information on thermocouple compensation wire selection, please refer to the thermocouple compensation wire introduction sample.